Microstructural stability of TMS-238™ Ni-base superalloy during long-term exposure at high temperature

Abstract

The microstructure evolution in Re–Ru containing high generation Ni-base single crystal superalloy has been investigated during long-term isothermal exposure at 1000°C. The chemical and physical characteristics are determined by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) measurements. In addition to the initial γ/γ’ phase structure, formation of HCP-structured Re–Ru–Ni-rich phase is confirmed. Based on high-resolution TEM imaging and phase structure analysis the theoretical atomistic model presenting the interfaces between the phases was constructed and evaluated with respect to precipitation kinetics. Growth of plate-like precipitates occurs mainly through the plate edge area due to stacking fault sequences between the surrounding matrix and the precipitates, while thickening is very limited due to good coherency with the surrounding phase in the longitudinal direction.

Effects of Long-Term Aging on Structure Evolution and Stress Rupture Property of DD6 Single-Crystal Superalloy

“…The volume fraction, size, distribution state, cubic metric of the γ phase, and the degree of lattice misfit with the γ phase in the matrix all affect the mechanical properties of the alloy [10][11][12][13]. The method of γ phase formation has been reported to have a significant effect on various properties of the alloy [14][15][16][17][18][19]. When the γ phase is uniformly and regularly distributed with a volume fraction of 65-70% and a size of 0.45-0.5 µm, its comprehensive mechanical performance is the optimal performance.…”